If your nails are yellow because you sttayed in with the naillil polish for a long time or whatever it is this tip will take all the yellow of your nails and leave them as they were before leaving no tracks:
1. remove everything from your nails
2.put some 3d crest white toothpaste  in one bowl(not too much but not too little)
3.squeeze a yellow lemon in the bowl too (yellow lemon)
4. mix it up well with a spoon.
5.take a toothbrush and dip it in then you press the toothbrush in your nails and push it down but not too hard just a gentle push.
6. redo the fifth step but this time you brush it on your nails.
7.wipe it out with some toilet paper.
8.take another bowl with some water on it  and put polident nettoyant pour cleaser.
9. watch it make some water while it gets together with the water.
10.take the tip of a spoon and mix it until its is desolved.
11.dip your nails on it.
12. take them out and dry them with a little towel then you might want to take a brush and brush them dosen't matter, just brush them dry.
13.wipe them out with a towel and for finishing put some shine nail polish on your nails
Enjoy your white and healthy nails!!!!!!!!